Heretofore, a hydraulic stepless transmission in which a first hydraulic system and a second hydraulic system are combined and a cylinder block common to the first and second hydraulic system rotates is well known. In such devices, a swash plate of the first hydraulic system, and a swash plate of the second hydraulic system are supported by a housing or the like, respectively, through combined thrust and radial bearings.
In order to suitably operate the above-mentioned combined thrust and radial bearings, it is necessary to apply a predetermined preload. Up to now, this preload has been applied by shim adjustment. However, since this shim adjustment is performed by the change in the number of sheets of shims, there is a problem in that tuning becomes complicated.